The bandwidth of the communication networks has been increased continuously as results of technological advances. However, the introduction of new services and the expansion of the existing ones have ...resulted in even higher demand for the bandwidth. This explains the many efforts currently being invested in the area of data compression. The primary goal of these works is to develop techniques of coding information sources such as speech, image and video to reduce the number of bits required to represent a source without significantly degrading its quality.
With the large increase in the generation of digital image data, there has been a correspondingly large increase in research activity in the field of image compression. The goal is to represent an image in the fewest number of bits without losing the essential information content within. Images carry three main type of information: redundant, irrelevant, and useful. Redundant information is the deterministic part of the information, which can be reproduced without loss from other information contained in the image. Irrelevant information is the part of information that has enormous details, which are beyond the limit of perceptual significance (i.e., psychovisual redundancy). Useful information, on the other hand, is the part of information, which is neither redundant nor irrelevant. Human usually observes decompressed images. Therefore, their fidelities are subject to the capabilities and limitations of the Human Visual System.
This paper provides a survey on various image compression techniques, their limitations, compression rates and highlights current research in medical image compression.
Summary
Sarcopenia was reported to be significantly associated with osteoporosis. In this study, we reported for the first time that sarcopenia was an independent risk predictor of osteoporotic ...vertebral compression refractures (OVCRFs). Other risk factors of OVCRFs are low bone mass density T-scores, female sex, and advanced age.
Introduction
The purpose of this study was to investigate the association between osteoporotic vertebral compression refractures (OVCRFs) and sarcopenia, and to identify other risk factors of OVCRFs.
Methods
We evaluated 237 patients with osteoporotic vertebral compression fracture who underwent percutaneous kyphoplasty (PKP) in our hospital from August 2016 to December 2017. To diagnose sarcopenia, a cross-sectional computed tomography (CT) image at the inferior aspect of the third lumbar vertebra (L3) was selected for estimating muscle mass. Grip strength was used to assess muscle strength. Possible risk factors, such as age, sex, body mass index (BMI), bone mineral density (BMD), location of the treated vertebra, anterior-posterior ratio (AP ratio) of the fractured vertebra, cement leakage, and vacuum clefts, were assessed. The multivariable analysis was used to determine the risk factors of OVCRFs.
Results
During the follow-up period, OVCRFs occurred in 64 (27.0%) patients. Sarcopenia was present in 48 patients (20.3%), including 21 OVCRFs and 27 non-OVCRFs patients. Sarcopenia was significantly correlated with advanced age, lower BMI, lower BMD, and hypoalbuminemia. Compared with non-sarcopenic patients, sarcopenic patients had higher OVCRFs risk. In univariate analysis, sarcopenia (
p
= 0.003), female (
p
= 0.024), advanced age (≥ 75 years;
p
< 0.001), lower BMD (
p
< 0.001), lower BMI (
p
= 0.01), TL junction (vertebral levels at the thoracolumbar junction) (
p
= 0.01), cardiopulmonary comorbidity (
p
= 0.042), and hypoalbuminemia (
p
= 0.003) were associated with OVCRFs. Multivariable analysis revealed that sarcopenia (OR 2.271; 95% CI 1.069–4.824,
p
= 0.033), lower BMD (OR 1.968; 95% CI 1.350–2.868,
p
< 0.001), advanced age (≥ 75 years; OR 2.431; 95% CI 1.246–4.744,
p
= 0.009), and female sex (OR 4.666; 95% CI 1.400–15.552,
p
= 0.012) were independent risk predictors of OVCRFs.
Conclusions
Sarcopenia is an independent risk predictor of osteoporotic vertebral compression refractures. Other factors affecting OVCRFs are low BMD T-scores, female sex, and advanced age.
The mainstay treatment for Degenerative Cervical Myelopathy (DCM) is surgical decompression. Not all cases, however, are suitable for surgery. Recent international guidelines advise surgery for ...moderate to severe disease as well as progressive mild disease. The goal of this study was to examine the factors in current practice that drive the decision to operate in DCM.
Retrospective cohort study.
1 year of cervical spine MRI scans (N = 1123) were reviewed to identify patients with DCM with sufficient clinical documentation (N = 39). Variables at surgical assessment were recorded: age, sex, clinical signs and symptoms of DCM, disease severity, and quantitative MRI measures of cord compression. Bivariate correlations were used to compare each variable with the decision to offer the patient an operation. Subsequent multivariable analysis incorporated all significant bivariate correlations.
Of the 39 patients identified, 25 (64%) were offered an operation. The decision to operate was significantly associated with narrower non-pathological canal and cord diameters as well as cord compression ratio, explaining 50% of the variance. In a multivariable model, only cord compression ratio was significant (p = 0.017). Examination findings, symptoms, functional disability, disease severity, disease progression, and demographic factors were all non-significant.
Cord compression emerged as the main factor in surgical decision-making prior to the publication of recent guidelines. Newly identified predictors of post-operative outcome were not significantly associated with decision to operate.
•The development and characteristics of low temperature combustion are reviewed.•The various modes of achieving low temperature combustion are analyzed fuel wise.•The effects of various fuels on low ...temperature combustion are discussed.•Limitations and key factors of low temperature combustion engines are pointed out.•Vast experimental data on low temperature combustion for many fuels are tabulated.
The fast rate of depletion of fossil fuel resources due to increasing demands and the adverse environmental impact by the automotive engines forced researchers to develop alternative strategies to meet the stringent emission norms in terms of oxides of nitrogen and particulate matter. In this regard, low temperature combustion is one of the promising advanced in-cylinder combustion strategies for reducing both oxides of nitrogen and particulate matter emissions simultaneously with a beneficial effect on specific fuel consumption. The low temperature combustion is achieved through homogeneous charge compression ignition, premixed charge compression ignition, reactivity controlled compression ignition and gasoline compression ignition. In this paper, an attempt is made to assemble and summarize a listing of important research articles on low-temperature combustion using a wide variety of conventional and alternate renewable fuels. The effect of low-temperature combustion on engine performance and emission characteristics over a wide range of engine test conditions and the challenges faced in these strategies are also described. From the assemblage of articles on low-temperature combustion using conventional and renewable fuels, it is understood that this strategy can help in achieving better performance, lower cylinder pressure and heat release rate, and simultaneous reductions of nitrogen oxides and particulate matter, but typically with an increase in carbon monoxide and hydrocarbon emissions. This literature review is expected to be useful to the researchers for understanding the concept, challenges, and the state-of-the-art of the different modes of low-temperature combustion using conventional and sustainable alternate fuels.
This paper presents a novel data compression and transmission scheme for power reduction in Internet-of-Things (IoT) enabled wireless sensors. In the proposed scheme, data is compressed with both ...lossy and lossless techniques, so as to enable hybrid transmission mode, support adaptive data rate selection and save power in wireless transmission. Applying the method to electrocardiogram (ECG), the data is first compressed using a lossy compression technique with a high compression ratio (CR). The residual error between the original data and the decompressed lossy data is preserved using entropy coding, enabling a lossless restoration of the original data when required. Average CR of 2.1× and 7.8× were achieved for lossless and lossy compression respectively with MIT/BIH database. The power reduction is demonstrated using a Bluetooth transceiver and is found to be reduced to 18% for lossy and 53% for lossless transmission respectively. Options for hybrid transmission mode, adaptive rate selection and system level power reduction make the proposed scheme attractive for IoT wireless sensors in healthcare applications.
Summary Background Drawbacks exist with the standard treatment (four-layer compression bandages) for venous leg ulcers. We have therefore compared the clinical effectiveness and cost-effectiveness of ...two-layer compression hosiery with the four-layer bandage for the treatment of such ulcers. Methods We undertook this pragmatic, open, randomised controlled trial with two parallel groups in 34 centres in England and Northern Ireland. The centres were community nurse teams or services, family doctor practices, leg ulcer clinics, tissue viability clinics or services, and wound clinics. Participants were aged 18 years or older with a venous leg ulcer and an ankle brachial pressure index of at least 0·8, and were tolerant of high compression. We randomly allocated participants (1:1) to receive two-layer compression hosiery or a four-layer bandage, using a remote randomisation service and prevalidated computer randomisation program. Participants were stratified by ulcer duration and ulcer area with permuted blocks (block sizes four and six). The primary endpoint was time to ulcer healing, with a maximum follow-up of 12 months. Although participants and health-care providers were not masked to treatment allocation, the primary endpoint was measured by masked assessment of photographs. Primary analysis was intention to treat with Cox regression, with adjustment for ulcer area, ulcer duration, physical mobility, and centre. This trial is registered with the ISRCTN register, number ISRCTN49373072. Findings We randomly allocated 457 participants to the two treatment groups: 230 to two-layer hosiery and 227 to the four-layer bandage, of whom 453 (230 hosiery and 223 bandage) contributed data for analysis. Median time to ulcer healing was 99 days (95% CI 84–126) in the hosiery group and 98 days (85–112) in the bandage group, and the proportion of ulcers healing was much the same in the two groups (70·9% hosiery and 70·4% bandage). More hosiery participants changed their allocated treatment (38·3% hosiery vs 27·0% bandage; p=0·02). 300 participants had 895 adverse events, of which 85 (9·5%) were classed as serious but unrelated to trial treatment. Interpretation Two-layer compression hosiery is a viable alternative to the four-layer bandage—it is equally as effective at healing venous leg ulcers. However, a higher rate of treatment changes in participants in the hosiery group than in the bandage group suggests that hosiery might not be suitable for all patients. Funding NIHR Health Technology Assessment programme (07/60/26).
High Bit-Depth Medical Image Compression With HEVC Parikh, Saurin S.; Ruiz, Damian; Kalva, Hari ...
IEEE journal of biomedical and health informatics,
2018-March, 2018-03-00, 2018-3-00, 20180301, Letnik:
22, Številka:
2
Journal Article
Recenzirano
Efficient storing and retrieval of medical images has direct impact on reducing costs and improving access in cloud-based health care services. JPEG 2000 is currently the commonly used compression ...format for medical images shared using the DICOM standard. However, new formats such as high efficiency video coding (HEVC) can provide better compression efficiency compared to JPEG 2000. Furthermore, JPEG 2000 is not suitable for efficiently storing image series and 3-D imagery. Using HEVC, a single format can support all forms of medical images. This paper presents the use of HEVC for diagnostically acceptable medical image compression, focusing on compression efficiency compared to JPEG 2000. Diagnostically acceptable lossy compression and complexity of high bit-depth medical image compression are studied. Based on an established medically acceptable compression range for JPEG 2000, this paper establishes acceptable HEVC compression range for medical imaging applications. Experimental results show that using HEVC can increase the compression performance, compared to JPEG 2000, by over 54%. Along with this, a new method for reducing computational complexity of HEVC encoding for medical images is proposed. Results show that HEVC intra encoding complexity can be reduced by over 55% with negligible increase in file size.
Compression is an effective and recommended treatment for venous leg ulcers. Although the four-layer bandage (4LB) is regarded as the gold standard compression system, it is recognised that the ...amount of compression delivered might be compromised by poor application technique. Also the bulky nature of the bandages might reduce ankle or leg mobility and make the wearing of shoes difficult. Two-layer compression hosiery systems are now available for the treatment of venous leg ulcers. Two-layer hosiery (HH) may be advantageous, as it has reduced bulk, which might enhance ankle or leg mobility and patient adherence. Some patients can also remove and reapply two-layer hosiery, which may encourage self-management and could reduce costs. However, little robust evidence exists about the effectiveness of two-layer hosiery for ulcer healing and no previous trials have compared two-layer hosiery delivering 'high' compression with the 4LB.
Part I To compare the clinical effectiveness and cost-effectiveness of HH and 4LB in terms of time to complete healing of venous leg ulcers. Part II To synthesise the relative effectiveness evidence (for ulcer healing) of high-compression treatments for venous leg ulcers using a mixed-treatment comparison (MTC). Part III To construct a decision-analytic model to assess the cost-effectiveness of high-compression treatments for venous leg ulcers.
Part I A multicentred, pragmatic, two-arm, parallel, open randomised controlled trial (RCT) with an economic evaluation. Part II MTC using all relevant RCT data - including Venous leg Ulcer Study IV (VenUS IV). Part III A decision-analytic Markov model.
Part I Community nurse teams or services, general practitioner practices, leg ulcer clinics, tissue viability clinics or services and wound clinics within England and Northern Ireland.
Part I Patients aged ≥ 18 years with a venous leg ulcer, who were willing and able to tolerate high compression.
Part I Participants in the intervention group received HH. The control group received the 4LB, which was applied according to standard practice. Both treatments are designed to deliver 40 mmHg of compression at the ankle. Part II and III All relevant high-compression treatments including HH, the 4LB and the two-layer bandage (2LB).
Part I The primary outcome measure was time to healing of the reference ulcer (blinded assessment). Part II Time to ulcer healing. Part III Quality-adjusted life-years (QALYs) and costs.
Part I A total of 457 participants were recruited. There was no evidence of a difference in time to healing of the reference ulcer between groups in an adjusted analysis hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.79 to 1.25; p = 0.96. Time to ulcer recurrence was significantly shorter in the 4LB group (HR = 0.56, 95% CI 0.33 to 0.94; p = 0.026). In terms of cost-effectiveness, using QALYs as the measure of benefit, HH had a > 95% probability of being the most cost-effective treatment based on the within-trial analysis. Part II The MTC suggests that the 2LB has the highest probability of ulcer healing compared with other high-compression treatments. However, this evidence is categorised as low to very low quality. Part III Results suggested that the 2LB had the highest probability of being the most cost-effective high-compression treatment for venous leg ulcers.
Trial data from VenUS IV found no evidence of a difference in venous ulcer healing between HH and the 4LB. HH may reduce ulcer recurrence rates compared with the 4LB and be a cost-effective treatment. When all available high-compression treatments were considered, the 2LB had the highest probability of being clinically effective and cost-effective. However, the underpinning evidence was sparse and more research is needed. Further research should thus focus on establishing, in a high-quality trial, the effectiveness of this compression system in particular.
Current Controlled Trials ISRCTN49373072.
This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 57. See the NIHR Journals Library website for further project information.
Malignant spinal cord compression (MSCC) is one of the most devastating complications of cancer. Patients often present with a history of progressive pain, paralysis, sensory loss, progressive spinal ...deformity, and loss of sphincter control. It is an emergency that requires rapid decision making on the part of several specialists, given the risk of permanent spinal cord injury or death. The goals of treatment in spinal metastases are pain control and improvement of neurological function in order to achieve better quality of life (QoL). The standard of care in most cases is rapid initiation of corticosteroids in combination with either surgical decompression in case of an operable candidate, followed by radiation therapy (RT) or RT alone. Surgery is associated with improved outcomes, but is not appropriate for many patients presenting with advanced symptoms of MSCC, such as paralysis, or those with a poor performance status, or cachexic state, as well as altered mental conditions, co-morbidities, surgical risks, and limited life expectancy. On the other hand, aggressive surgical treatment and post-operative RT is advocated for those with more favorable prognosis, or who are expected to have higher neurological recovery potential. Many candidates may require for combined anterior and posterior approaches to effectively deal with the compressive pathology and stabilize the spine. Most patients are presently treated by primary RT, given with the aim of improving function and symptom management. However, there is still debate regarding the most appropriate RT schedule. Rehabilitation can serve to relieve symptoms, QoL, enhance functional independence, and prevent further complications. Ambulatory status has been found to be an important prognostic factor for patients with MSCC.
The use of next-generation and high-resolution imaging sensors is gaining interest for space missions, because of their properties for identification and exploration purposes. It is expected that the ...demand for video sensors in the space industry will increase during the next years, mainly for monitoring and exploration missions. In this context, onboard video compression techniques emerge as mandatory, because memory resources are available on space missions and the downlink bandwidth with ground prevents for the transmission of raw video, especially when near real-time capabilities are required. The complexity of the current commercial video encoders supposes a challenge for their implementation on the hardware used on space missions, because of their high architectural complexity and computational requirements, deriving in an area overhead and an unacceptable power consumption. In this context, we propose the use of the CCSDS-123.0-B-2 standard, originally focused on the near-lossless on-board compression of multispectral and hyperspectral images, for compressing panchromatic video. The proposed solution presents low complexity, because it is specifically designed for working on space missions and also has the capability of compressing both 3-D images and panchromatic video by using a single processing core. Results demonstrate that this solution achieves high compression ratios, maintaining a considerable video quality after reconstruction on ground and achieving a fine-grain control of the losses introduced in the compression chain.
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